if he's sleeping and eating well I wouldn't panic too much - you can by fess nose drops (saline) with an aspirator from the chemist which can help clear the passages etc - although the child is often not real happy about the aspirator. Otherwise keep an eye on him for temperatures, lethargy, rashes etc that may be the sign of a different infection and may need attention. Good feeding and lots of wet nappies is all a good sign though.

Hope his little nose clears soon.